Im new at TRLE, i have played Tomb Raider since i was a child, and i have ever wanted to make a custom level with TR3 india wads, but... there is a problem, i don't know how to use wad merger or how to configure it because when i make a custom wad and save it it says that some sound samples are missing and level does not work, i don't know how to explain but please i need help with custom wads.

When it comes to WADs, I always start with an existing WAD (like tut1, for example) and add items to it. WADs are not compatible between TR games because there are specific objects that only work in each game. In other words, you can't simply copy a TR3 wad into your level editor folder and have it work. Objects that are specific to a game like TR3 have to be adapted to work in the TRLE.

I'll try to walk you through it step by step. First, what TR3 WAD are you trying to use? Is it one you downloaded online, or one that you're ripping directly from the game?